Improving Transformer Energy Performance with Copper

Higher copper content in transformers improves energy performance and consequently lowers lifecycle costs in most cases

The various costs incurred during the long life of a transformer can be broadly categorized into purchase, operating and end-of-life costs. Of these, the operating costs – principally comprising the cost of energy losses in the transformer – are dominant. Therefore the astute purchaser will give a high weightage to the transformer’s energy performance in his decisions and will not base these on direct costs alone.

Transformer designers have a mix of options available for improving energy performance – principally the use of larger core and conductor cross-sections, or a lower loss core material, or a better conductor, i.e. copper. The optimization of this mix is done on an ongoing basis by designers and manufacturers, based on relative material costs at the given time and the specific conditions of procurement on energy performance. This is the reason for the variety of transformer designs seen in the market.

European Commission study

In preparing for the implementation of the Energy Related Products (ERP) Directive (2009/125/EC) related to power and distribution transformers, the European Commission commissioned a study by VITO and BIOIS to investigate, among others factors, the improvement potential in the design of various types and sizes of transformers in terms of least lifecycle costs. For each base case, the study worked out various design options and compared these for their improvement potential over the respective base case. The results show that in all cases investigated, the transformer design option that gives the least lifecycle cost has lower energy losses and uses substantially more copper than the respective base case.

KEMA study

An independent study across the European Union carried out by KEMA came to a similar conclusion – power transformers use more copper wherever a higher financial weightage (loss factor) is given to energy performance by the purchaser.


Thus it can be concluded that the higher copper content in transformers results in an improved energy performance and consequently in lower lifecycle costs in most cases.


  • VITO and BIOIS study for preparing the implementation of the new Ecodesign or Energy Related Products (ERP) Directive (2009/125/EC) related to power and distribution transformers, on behalf of the European Commission DG ENTR unit B1 OT2: Distribution and power transformers Tasks 1 – 7 Contact VITO: Paul Van Tichelen, Contact BIOIS: Shailendra Mudgal, 2010/ETE/R/106, January 2011
  • Drivers for Copper use in Power Transformers, S.A.A. Houtepen, J. Bloem KEMA, Arnhem 20 December 2011 , 74101182-ETD/SUP 11-2903